1. Progamic paragamy: the fusing nuclei are the normal gametonuclei of the progamous cell (ovum which has formed one polar body in Pterotrachæa, Astropecten). 2. Apocytial paragamy: the vegetative nuclei of an apocytium fuse to form a zygote nucleus ('oospores' of Saprolegniew). 4. On Recent Investigations of the Marine Biological Association (Fishery and Physical). By W. L. CALDERWOOD, Director. 1. Fishery Investigations. In the absence of general returns as to the increase or decrease of any particular fishery in a given locality, we at Plymouth are from time to time discussing the local fisheries. Papers have now been published on the mackerel, herring, long-line, i.e. cod, conger, skate, &c., pilchard, and lobster fisheries, the object being to show, as time goes on, any changes that may take place in the relative abundance of the various fishes. Three investigations, started within the present year, which it is hoped will prove of great value to the fishing population of this country, are: a. The attempt to produce an artificial bait for use in long-line fishing. This investigation is being carried on by a chemist from Professor Meldola's laboratory. Considerable advance has been already made towards a satisfactory solution of this difficult problem. b. An inquiry into the occurrence of anchovies off the south-west coast of England. At present no net small enough in the mesh to capture anchovies is employed, but these fishes appear so often when the ordinary pilchard nets become entangled, as to suggest that they must be present in considerable quantities. Anchovy nets have therefore been constructed and will be used during the pilchard season this autumn. c. An investigation into the condition of the North Sea Fisheries, at present declared to be rapidly declining :— 1. To draw up a history of the North Sea trawling grounds, comparing the present condition with the condition, say, twenty to thirty years ago, when comparatively few boats were at work. 2. To continue, verify, and extend observations as to the average sizes at which prime fish (soles, turbot, brill) become sexually mature. 3. To collect statistics as to the sizes of all fish captured in the vicinity of the Dogger Banks and the region lying to the eastward, so that the number of immature fish annually captured may eventually be estimated. 4. To make experiments with beam-trawl nets of various meshes, with a view to determine the relation, if any, between size of mesh and size of fish taken. 2. Physical Investigations.--A regular survey of the English Channel has been commenced not only in the deep water but in the various estuaries. A Meteorological Station of the second order has been recently established where observations at 9 A.M. and 9 P.M. will be taken daily with wet and dry bulb thermometers, barometer, rain-gauge, anemometer, and sunshine recorder. 5. On the Growth of Food-fishes and their Distribution at different ages. By J. T. CUNNINGHAM, M.A. As the result of observations extended over the past two years, I have reached some conclusions as to the rate of growth of certain food-fishes, the age at which they begin to breed, and their distribution at different ages. (1) Rate of growth and age of sexual maturity.-Numerous specimens of the Flounder (Pl. flesus), were reared from the larval state in the Aquarium of the Plymouth Laboratory. Measured in April, when a year old, they varied from 4 to 19 cm. (about 1 to 7 inches). Specimens obtained in the Cattewater, and known to be not less than a year old, are from 12 to 19 cm. in length. None of these captive flounders nor any taken in the Cattewater were sexually mature, but, according to Dr. Fulton, of the Scottish Fishery Board, sexually mature flounders have been observed which were only 7 inches long. I conclude therefore that (a) the rate of growth varies greatly for different individuals, but its maximum for the first year is 19 cm. or 73 inches, (b) sexual maturity is not reached till the end of the second year, although the minimum size of sexually mature individuals may be slightly exceeded by some specimens in one year's growth. I have obtained similar results for the Plaice (Pl. platessa) and the Dab (Pl. limanda). (2) Distribution.-The young of the above-mentioned species in their first year, and of certain round fish, especially Gadus luscus and G. minutus, occur in shallow water, within the 10-fathom line. But there has hitherto been considerable difficulty in obtaining young specimens of other more valuable species in order to study their rate of growth. These species, namely, the Sole, Turbot, Brill, Lemon Sole, Megrim (Arnoglossus megastoma), do not pass the first year of their lives in shallow water. I have obtained young Soles in the larval state in tidal pools at Mevagissey, and young Turbot and Brill 2 to 3 cm. in length are commonly found from June to August in Plymouth Sound and Sutton Pool, swimming at the surface in a semimetamorphosed stage. Soles a little over 16 cm. in length are frequently taken in Plymouth Sound in summer; these are just over one year old and are not sexually mature. Turbot 23 to 34 cm. long I have taken in 5 to 7 fathoms; these also are over one year old and not sexually mature. But the young stages between 3 months and 12 months old have not been taken in shallow water, and apparently live at depths greater than 10 fathoms. It seems that our commoner and more valuable food-fishes do not attain to sexual maturity till the end of their second year, that their size at this age is subject to great individual variation, and that the young in the first year of growth have a characteristic distribution. Investigation of the deeper water from this point of view is now being carried on at Plymouth. 6. The Reproduction of the Pilchard. By J. T. CUNNINGHAM, M.A. In a paper published in the 'Journal' of the Marine Biological Association in 1889, I described the egg of the Pilchard, obtained from the sea by the tow-net, and identified by comparison with the mature egg taken from ripe female Pilchards. The distinguishing features are four in number: (1) size 165 to 172 mm. in diameter, (2) the very large perivitelline space, (3) the vesicular composition of the yolk, (4) the large single oil-globule in the yolk. 2 Professor Pouchet, who has studied the Sardine at the Marine Laboratory of Concarneau, persists in denying that this egg obtained by me is that of the Pilchard, believing that the egg of the Sardine or Pilchard is not pelagic. My identification confirmed that suggested by Raffaelle from observations at Naples. Marion at Marseilles has entirely confirmed my results and also traced the growth of the Sardine at that place, showing that it reaches a length of 9 to 13 cm. in one year. This year at Plymouth, in June, I obtained ripe female Pilchards, but no males. However, I placed the ripe unfertilised ova in clean sea-water, and found that after twenty-four hours the ova were alive and floating, the perivitelline space was formed, and the eggs presented all the characteristic peculiarities I had previously attributed to the ova of the Pilchard. I also at the same time obtained the same eggs in process of development from the sea, by means of the tow-net. In July I obtained the alevins of the Pilchard at the surface near the Eddystone, a number of specimens varying from 8 to 2.5 cm. in length. I hope to trace their further growth and compare it with that of the Mediterranean Sardine. The ripe Pilchards at Plymouth are 23 to 25 cm. long, ripe adult Sardines in the Mediterranean are only 15 to 18 cm. See Rapport sur le Lab. de Concarneau for 1889,' in Journal d'Anat. et de Physiol., 1890. 2 Annales du Musée d'Histoire Nat. de Marseille, 'Zoologie Appliquée,' 1891. 7. Observations on the Larvae of Palinurus vulgaris. On July 9 and 16 of the present year I obtained a large number of the Phyllosoma larvæ of Palinurus vulgaris. Previously, in the summer of 1889, the eggs of this species were hatched in the tanks of the Plymouth Laboratory of the Marine Biological Association, and I preserved a number of the newly hatched larvæ. The latter are 3.1 mm. in length from the front of the cephalon to the end of the abdomen. The largest of these taken in the sea are 7 mm. in length. I find that the first maxilliped is not absent altogether at any of the stages I have obtained; it is represented in the newly hatched larvæ as a small but distinct conical process, and does not increase or decrease in any way up to the oldest stage I have obtained. In the Phyllosoma of 7 mm. the antennæ are more developed, the fourth and fifth ambulatory appendages, present at hatching as minute processes, have developed considerably, the fourth being already biramous. Richter's statement therefore ('Zeitsch. f. wiss. Zoologie,' 1873) that the first maxilliped is entirely absent in Palinurus phyllosoma in the earliest stages is not true in the case of P. vulgaris. I find also that stages of Phyllosoma figured and described by Claus (ibid. 1863) from 3.5 mm. to 21 mm. in length, are certainly larvæ of P. vulgaris, although this identification seems never to have been definitely made before. 8. Distribution of Crystallogobius Nilssonii, Gill. By J. T. CUNNINGHAM, M.A. I obtained this species in large numbers on July 9 of the present year when trawling with a small beam-trawl about two miles north of the Eddystone, in about twenty-seven fathoms of water. Day mentions only one specimen found in British waters, namely, one taken by Thos. Edward in a rock-pool at Banff. This specimen was a male. The species is distinguished by having only two rays in the anterior dorsal fin in the male, this fin and the pelvic fins being rudimentary in the female. The fish is quite transparent when alive, and scaleless; the mature male is about 4 cm. in length, the female smaller. There is a good paper on the species by R. Collett, of Christiania, in Proc. Zool. Soc.' for 1878. It is there stated that the fish is fairly common in the Christiania Fjord, thirty specimens having been taken there. A few specimens have been taken near Bergen, at Christiansund, and also in Bohuslan, in Sweden. I took in a single haul about 100 specimens, more than all those that had been taken in Norway and Sweden since 1843, when the species was first discovered. All my specimens were adult or nearly so, which agrees with Collett's conclusion that the fish is an annual, dying after breeding. Mr. E. W. L. Holt also took many specimens of the same species in Ballinskelligs Bay, thirty fathoms, on August 21, 1890. The shrimp trawl used by me was lined inside with mosquito netting, on purpose to retain small animals. Probably the species is fairly abundant between twenty and thirty fathoms, on smooth sandy ground, all along the British and Irish coasts. MONDAY, AUGUST 24. The following Papers were read: 1. Facts regarding Prothalli and the Propagation of Ferns. Occasionally in a batch of seedling ferns there will occur several plants of some strangely marked variety identical in their characters and growing so closely together that it is difficult to separate them. I have long suspected these were produced on the same prothallus; indeed this seemed evident in four instances of remarkable seedling Athyriums, yet the development was too far advanced for absolute certainty. To examine this carefully, a number of Scolopendriums were planted in the prothallus state, and on the young fronds appearing, two were noticed identical in character and unusual in form, which when examined were found to have their origin in one well-developed prothallus. With a penknife it was possible to divide the prothallus so as to secure the two plants, which were planted in a pan and have not since been disturbed. Prothalli were then planted from a pan of mixed muricate and undulate Scolopendriums, and these were divided before the formation of fronds into two equal parts, in some examples the two plants resulting were alike, in others they differed but showed their muricate and undulate origin. The next experiment was dividing the prothallus into four equal parts. This was done in January 1888. Every division grew and spread in a more bush-like manner than is the case with undivided prothalli, but up to July 1890 there was no sign of any frond. It appeared evident that the male and female organs of generation were on separate divisions. To test this, in May 1890 another prothallus was planted in close proximity to one of these, in fact made to actually intermingle, and in August fronds appeared. The other divisions except four were similarly treated, and all have now produced fronds. The spores had been sown in August 1887, and divided on January 12, 1888, so that the prothallus exhibited has been in this condition four years. The usual time from prothallus to frond being only a few months. In an interesting example of the lady fern (alluded to in the next paper), a prothallus produced three plants exactly alike and having two kinds of fronds. It was from a mixture of eight varieties, and these show the parentage of six, and now and then seven. They have the lax pinne of uncum, the cruciate pinna of Victoria, the projected pinnæ of projectum, the lunulate pinnules of Frizelliæ, the cruciate pinnules of crucipinula, the truncate terminals of truncatum, and occasionally the cresting of multifidum. This fern has reproduced six and occasionally seven characters. According to the doctrine of probability it is 720 to 1 against the production of six varieties on the same plant, and 5,040 against seven. Turning to other means of reproduction, experiments are required in order to ascertain why the bulbils that form on some fronds do not always produce plants like the parent, and why it is possible to transfer the bulb-bearing character to other varieties. Scolopendrium densum often produces much more coarse and less divided ferns than itself. [Densum and one of its coarse bulbils were exhibited.] The beautiful plumose shield fern known as plumosodivisolobum has produced two plants from its bulbils that are strikingly distinct from the parent and each other; one is densely imbricate and procumbent like the parent, whilst the other is as finely divided as Todea superba, and is erect in habit." Again, aposporous plants, that is those raised from the prothalli direct without the intermediate spore, also vary. [An aposporous plant of Clarissima of the Lady fern was described.] Even plants raised from bits of the stipes of plumose Scolopendriums produced a marginal belt. There are so many truths yet to learn with regard to ferns that it is desirable that some younger man should take up these inquiries. 2. On Ferns and their Multiple Parents. By E. J. LowE, F.R.S., F.L.S. Colonel Jones and myself read a joint paper on abnormal Ferns at the Bath meeting of the British Association, which is printed in full with illustrations in the third volume of the Annals of Botany.' The present paper is a report on further experiments, and of the surprising discoveries that have resulted. Since 1887 other hybrids have been obtained, and although these hybrids are more or less sterile, a few plants (grandchildren of the original parents) have been raised, and they differ so much from the parent that nearly all resemblance has disappeared. What will be the characters of the great-grandchildren is now in course of proof. It is very different in the case of the offspring of crossed varieties: they are copiously fertile, and when sown alone reproduce their varietal form. Not only have certain forms been imparted to other Ferns, but even variegation, notably so in the Shield Fern and the Hart's-tongue. In the latter spores from a normal but variegated form were sown thickly with a plumose (or crispum form) and a branching form, and their offspring have become variegated. By sowing a muriate and a plumose Hart's-tongue together, muriate plumose varieties have also resulted. For illustrating multiple parentage the Hart's-tongue has been selected, as the simple, strop-shaped fronds are best able to show the various departures from the normal form. In repeating the experiment of mixed spores the varieties in each case have been limited to three or four, so that the resultant changes could be more narrowly investigated. Distinct mixtures were sown in 1887, 1888, 1889, and 1890, and the results in all the experiments established the fact that the antheridia of more than one variety have assisted in the impregnation. The varieties had conspicuously distinct characters, and in the example of 1888 the spores were gathered from a dwarf spiral form, a muricate or warty form, an undulate and a ramose one; more exactly speaking, the varieties were spirale, undulatum, muricatum, and keratoides. The parents were exhibited as well as three of their children, the latter having the names of quadriparens, Darwiniana, and echinatum. These unmistakably show on each plant the characters of the whole four parents. In the hundreds of these seedlings, as might be expected, the majority show only the characters of two parents, in a less though considerable number the characters of three, whilst a small number exhibit those of the four parents. The plants in the 1889 experiments are from a muricate, a branched, and a cup-bearing form, known as peraferens, the object being to obtain cups on a branching muricate Fern, as this was a desideratum. There was no previous example of more than one cup on a frond. In the seedlings a divided frond can be observed with cups on each division, a tasselled form with a rosette in place of an actual cup, and in another example a marginal row of small cups; and all are muricate. It is worth remarking that the seedlings from mixed spores never seem to produce any plants that exactly resemble any one variety; they are all combinations; in other words, antherozoids from a number of different antheridia are required for fertilisation. In sowing varieties of the Lady Fern I have raised the combination of five and six. This is alluded to in my paper On Prothalli.' These plants that give evidence of multiple parentage were obtained in the identical manner formulated before they had any existence. Spores require to be sown thickly to enable the prothalli to intermingle, otherwise they are only fertilised from the same prothallus. If we take the reasoning of Sir John Herschel on the doctrine of probability, and apply it to these experiments, the chances against the reasoning adopted being incorrect are as great as that of the haphazard distribution of the stars. These experiments regarding the changes in animal and vegetable life were commenced forty years ago. Bearing to some extent on this subject, experimenting on the Mimulus, a yellow variety was crossed with a spotted one, and the seedlings were spotted; later on, and further up the same stem, two blooms were this time crossed with a yellow one, but the seedlings were still spotted. The effect of the first cross had become a part of the life-history of the plant; in a second experiment the same plant was simultaneously crossed with pollen from two other varieties, and several of the seedlings are combinations of the three. It requires dexterity in crossing the Mimulus, as the pistil is as sensitive as the sensitive Mimosa. Natural changes are slow, but culturally we can accelerate that process that continues age after age. The germ once changed, the new element is retained, which becomes combined with others until the normal appearance is lost. The illustration of the Hart's-tongue shows this alteration, helped on as it were by artificial means that have accelerated the process, and these changes will continue whilst the world lasts. Affectionate respect causes tablets to be erected in memory of the departed, but age obliterates this record. It is, however, far different with the philosopher who has discovered great truths; he has erected a monument to himself more lasting than brass.' Time wears away the hardest 1891. ΣΥ |